/* Copyright (c) 2020 XEPIC Corporation Limited */
/*
 * Copyright (c) 2002-2018 Stephen Williams (steve@icarus.com)
 *
 *    This source code is free software; you can redistribute it
 *    and/or modify it in source code form under the terms of the GNU
 *    General Public License as published by the Free Software
 *    Foundation; either version 2 of the License, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 * USA.
 */

#include <cassert>
#include <climits> /* for CHAR_BIT */
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include "config.h"
#include "vpi_priv.h"

extern const char hex_digits[256];

void vpip_hex_str_to_vec4(vvp_vector4_t& val, const char* str) {
  unsigned str_len = strlen(str);
  unsigned skip_chars = 0;
  const char* tstr = str;
  /* Find the number of non-numeric characters. */
  while ((tstr = strpbrk(tstr, "-_"))) {
    skip_chars += 1;
    tstr += 1;
  }
  vvp_vector4_t tval(4 * (str_len - skip_chars));
  skip_chars = 0;
  for (unsigned idx = 0; idx < tval.size(); idx += 1) {
    unsigned tmp;
    unsigned bit_off = idx % 4;
    unsigned str_off = idx / 4;
    char ch;

    assert(str_off + skip_chars < str_len);
    /* Skip any "_" characters in the string. */
    while ((ch = str[str_len - str_off - 1 - skip_chars]) == '_') {
      skip_chars += 1;
      assert(str_off + skip_chars < str_len);
    }

    /* If we find a "-" it must be at the head of the string. */
    if (ch == '-') assert(0);

    switch (ch) {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        tmp = ch - '0';
        tval.set_bit(idx, ((tmp >> bit_off) & 1) ? BIT4_1 : BIT4_0);
        break;
      case 'a':
      case 'b':
      case 'c':
      case 'd':
      case 'e':
      case 'f':
        tmp = ch - 'a' + 10;
        tval.set_bit(idx, ((tmp >> bit_off) & 1) ? BIT4_1 : BIT4_0);
        break;
      case 'A':
      case 'B':
      case 'C':
      case 'D':
      case 'E':
      case 'F':
        tmp = ch - 'A' + 10;
        tval.set_bit(idx, ((tmp >> bit_off) & 1) ? BIT4_1 : BIT4_0);
        break;
      case 'x':
      case 'X':
        tval.set_bit(idx, BIT4_X);
        break;
      case 'z':
      case 'Z':
        tval.set_bit(idx, BIT4_Z);
        break;
      default:
        /* Return "x" if there are invalid digits in the string. */
        fprintf(stderr,
                "Warning: Invalid hex digit %c(%d) in "
                "\"%s\".\n",
                ch, ch, str);
        for (unsigned jdx = 0; jdx < val.size(); jdx += 1) {
          val.set_bit(jdx, BIT4_X);
        }
        return;
    }
  }

  /* Make a negative value when needed. */
  if (str[0] == '-') {
    tval.invert();
    tval += (int64_t)1;
  }

  /* Find the correct padding value. */
  vvp_bit4_t pad;
  switch (tval.value(tval.size() - 1)) {
    case BIT4_X:  // Pad MSB 'x' with 'x'.
      pad = BIT4_X;
      break;
    case BIT4_Z:  // Pad MSB 'z' with 'z'.
      pad = BIT4_Z;
      break;
    case BIT4_1:  // If negative pad MSB '1' with '1'.
      if (str[0] == '-') {
        pad = BIT4_1;
        break;
      }
      // fallthrough
    default:  // Everything else gets '0' padded.
      pad = BIT4_0;
      break;
  }

  /* Copy the temporary value to the real value, padding if needed. */
  for (unsigned idx = 0; idx < val.size(); idx += 1) {
    if (idx < tval.size())
      val.set_bit(idx, tval.value(idx));
    else
      val.set_bit(idx, pad);
  }
}

void vpip_vec4_to_hex_str(const vvp_vector4_t& bits, char* buf, unsigned nbuf) {
  unsigned slen = (bits.size() + 3) / 4;
  assert(slen < nbuf);

  buf[slen] = 0;

  unsigned val = 0;
  for (unsigned idx = 0; idx < bits.size(); idx += 1) {
    unsigned vs = (idx % 4) * 2;

    switch (bits.value(idx)) {
      case BIT4_0:
        break;
      case BIT4_1:
        val |= 1 << vs;
        break;
      case BIT4_X:
        val |= 2 << vs;
        break;
      case BIT4_Z:
        val |= 3 << vs;
    }

    if (vs == 6) {
      slen -= 1;
      buf[slen] = hex_digits[val];
      val = 0;
    }
  }

  /* Fill in X or Z if they are the only thing in the value. */
  switch (bits.size() % 4) {
    case 1:
      if (val == 2)
        val = 170;
      else if (val == 3)
        val = 255;
      break;
    case 2:
      if (val == 10)
        val = 170;
      else if (val == 15)
        val = 255;
      break;
    case 3:
      if (val == 42)
        val = 170;
      else if (val == 63)
        val = 255;
      break;
  }

  if (slen > 0) {
    slen -= 1;
    buf[slen] = hex_digits[val];
  }
}
